Comparison of the PLL Control techniques applied in Photovoltaic System

The increasing demand for low-carbon power and concerns about the environment resulted in the proliferation of alternative sources of energy. Among these sources, the photovoltaic systems stand out. However, these systems produce energy in direct current and require power inverters to connect them to the electric grid. For this connection to be realized the generated signal must have the same parameters of amplitude, phase, and frequency of the electrical network. In this sense, Phase-Locked Loop (PLL) controllers are used to synchronize the output signal with the network signal. For this type of system there are several topologies, such as PLL Synchronous Reference Frame (SRF-PLL), Second-Order Generalized Integrator PLL (SOGI-PLL), Enhanced PLL (EPLL) and Quadrature PLL (QPLL). This work proposes to compare these four controller topologies applied to the inverter of the photovoltaic system connected to the electric grid.